Various seal members and waterproof housing structures allowing containers or enclosures to be closed have hitherto been proposed. For example, Japanese Patent Laid-Open No. 11-294593 describes a seal member that exhibits an excellent sealing property even when the container has a noncircular opening shape such as one including a linear part. Japanese Patent Laid-Open No. 2007-42842 describes a waterproof housing structure allowing a sufficient waterproof property to be maintained over a long period. A structure including an elastomer gasket sandwiched between a first enclosure section and a second enclosure section has been adopted as a waterproof structure for electronic apparatuses and the like. In such a waterproof structure, the gasket is compressed in a fitting direction.
An excellent waterproof property has recently been required even for small-sized enclosures for electronic apparatuses and the like.
However, if the gasket is compressed in the fitting direction, the gasket continues to exert a strong pressing force in a direction in which the enclosure is opened, as a result of the repulsive force of the gasket. Thus, the required strength of the enclosure needs to be ensured. However, it is likely that the strength for small-sized enclosures will be insufficient. Furthermore, as the enclosure is opened under the pressing force of the gasket, the compression amount of the gasket decreases. As a result, opening the enclosure even by a small amount may degrade the waterproof performance. Additionally, the possible friction between the gasket and the enclosure may make assembly of the enclosure difficult. Moreover, the gasket is often arranged like a frame along the outer peripheral edge of the gasket. However, if the outer periphery of the enclosure has a complicated shape, the gasket is expected to fail to be appropriately compressed, thus preventing the desired waterproof property to be ensured.
Such a problem may similarly occur when the seal member is used in a small-sized electronic apparatus or the like.